Means for the storage and transportation of a liquefied gas



May 9, 1961 J. J. HENRY 2,983,409

MEANS FOR THE STORAGE AND TRANSPORTATION OF A LIQUEFIED GAS Filed July2, 1958 FIG, 1

IN VEN TOR.

m 24 7 flziorneys 2,983,409 V MEANS FOR THE STORAGE AND TRANSPORTA- TIONOF A LIQUEFIED GAS James J. Henry, New York, N.Y., assignor, by nlesneassignments, to Conch International Methane Limited, Nassau, Bahamas, acorporation of the Bahamas Filed July 2, 1958, Ser. No. 746,138

3 Claims. Cl. 222-399 This invention relates to the storage and/ortransportation of liquefied natural gas and it relates more particularlyto means employed in combination with a liquefied methane storage tankfor controlling the flow of liquid into and out of the tank. I

As is well known, natural gas is available in excessive supply in someareas while a deficiency of natural gas or an equivalent fuel exists inmany other areas. Where the twoareas are connected by land, transmissionfrom the area of plentiful supply to an area where a deficiency existscan economically be effected by pipe line. Where the areas are connectedby water, pipe line transmission is not so practical and other meansmust be devised for making such gas economically available to such areaswhere the deficiency exists.

Transportation in a gaseous state is impractical because of the smallamount of gas that can be housed per unit volume of the container.Almost 600 times as much gas can be housed in an equivalent space at anequivalent pressure when the gas is reduced to a liquefied state. As aresult, it becomes practical and economically feasible to liquefy thenatural gas at the sourceof supply for transportation by ship in aliquefied state to the Patented May 9, 1961 operation of equipment. Theextreme cold must be 1 kept out of contact with the steel walls of theship since such walls lose their ductility at such low temperatures. Forthese and various other reasons, it is desirable to have means availablewhich avoid the necessity of moving parts for removal of the liquid fromthe tanks in the event of failure or an emergency or a like situationwhere it is desirable to eflect removal'of the liquid from the tanks bymeans other than the conventional extemal 'pumps. It is an object ofthis invention to provide means in the storage and transportation ofliquid which'has to be maintained at extremely'low temperature wherebythe liquid can be. removed from the storage container without thenecessity to make use of a power operated means or moving parts and itis a related object to provide emergency means forremoval of a coldboiling liquefied gas from storage tanks.

These and other objects and advantages of this in vention willhereinafter appear and for purposes of illustration, but not oflimitation, an embodiment of the invention is shown in the accompanyingdrawings in Figure 'l is a plan view of storage tanksmounted in the holdspace of a ship and elements employed in com-' bination therewith inaccordance with the practice of fill the ships tanks at theliquefaction'site and for conarea where a deficiency exists where theliquid is reformed to the gaseous state for use.

In commercial. practice, shipment will be made of the liquefied gas inlarge volume housed in suitable containers. Such containers of largecapacity cannot economically be fabricated to withstand high pressures.As a result,the liquefied gas will be housed in the containers at aboutatmospheric pressure and at a temperatureat or-below its'critical'temperature. For liquefied natural gas composed mostly ofmethane, the critical temperature level will be somewhat below 240 F.depending upon the amount of heavy hydrocarbons in the liquefied gas.

Thus use will be made of large tanks, such as tanks of 30 x 60 x 100feet, formed of a metal such as aluminum, alloy of aluminum, copper,stainless steel or the like metal capable of retaining its ductility atthe cold temperature of the liquid. The tanks will be mounted in thehold space of the ship substantially completely to fill the hold withthe exception of a relatively thick lining of insulation material forminimizing heat transfer.

Oils, gasolines, and the like petroleum products and other liquids havebeen transported in tanks or tankers but such materials are usuallyhoused in the storage containers at about ambient temperature. Thus, noparticular problems are raised in the storage of a liquid or its flowinto and out of the storage tanks. Where, however, the liquid to betransported comprises a liquefied gas having a critical vaporizationtemperature at its storage temperature of about 240 F., the problemsarising are entirely diflFerent than those of the transportation of aliquid at ambient temperature.

The extreme cold of the liquid and vapor raises certain problems such ascondensation and solidification of moisture from the atmosphere whichmay interfere with the nection with the shoretanks for" discharging theliquid ingtherefrom for communicating the main header with spray headslocated within the tanks for wetting down the walls and cooling down thetanks before flowing the liquid at'a more rapid-fate through thelines 18for'filling' the. tanks. Each of the branch lines is provided with agate valve 22 and 24 for controlling the flow of liquid. The liquid isdischarged from each of the tanks through a downpipe having its inlet atthe bottom of the tank. The opposite end of the pipe communicates theinlet with a pump 26 located outside of the tank and the pumps outletcommunicates with a branch pipe 28 leading into the header 16. A checkvalve 30 and a gate valve 32 are provided in each of the branch pipes.The foregoing comprises the normal means for filling and discharging thetanks with the liquefied natural gas.

Operative in combination therewith is a supplemental means foreflfecting the discharge of the liquid from the tanks into the header.Such means comprises a sealed housing 34 in the bottom of each tank.Each housing is provided with an inlet 36 in a side wall adjacent thebottom of the tank having a swing check valve 38 in the line 40 whichhas an open end in the liquid space near the bottom of the tank 12 andcommunicates with the inlet 36. The check valve closes in response topressure within the housing and opens automatically in response torelease of pressure within the housing.

Extending into the housing is a tubing 42 having its inlet 44 at thebottom of the housing and which extends outwardly from the housingthrough the top of the tank 12 to the main header 16. A gate valve 46and a check 3. valve 48 are provided in the part of the line 50 betweenthe tank and the header.

The housing is also provided with an inlet opening 52. The inlet openingcommunicates with a compressed gas header 54 throughaa tube 56 which hasathree-Way valve 58 in a portion outside of the tank and a gate valve 60and 62 on each side of the three-way valve. In one'position, the valvecommunicates the inlet 52 with the compressed gas header 54 while in theother position, the valve communicates the inlet 52 with a vapor header64.

The compressed gas in the compressed gas header can be an inert gas suchas nitrogen or carbon dioxide but it is preferred to make use of vaporsreleased from the housing or from the tank for recompression thereby toprovide a complete cycle which avoids the introduction of foreignmaterial into the system. ,The vapor removed can be recompressed to somehigher pressure such as 50 p.s.i. for use in the discharge cycle.

In operation, the valve 58 can be operated to communicate the compressedgas header 54 with the inlet 52 whereby vapors at a pressure of about 50p.s.i. enter the housing 34 to force the liquid therein through thetubing 42 to the liquid header 16 with the gate valve 46 in openposition and the check valve 48 opened in response to such pressure onthe liquid. When the housing 34 has been substantially completelyemptied of liquid, the threeway valve 58 can be operated to communicatethe inlet 52 with the vapor header whereby the housing 34 will berelieved of pressure. Under such circumstances, the head of liquid inthe tank will be effective to cause the swing valve 38 to open to enableliquid to flow through the line 40 into the housing 34 to fill thehousing. The vapor within the housing that is displaced by the liquidcan flow through the inlet 52 into the line 56 for passage to the vaporheader for recompression or disposal. When the housing 34 hasbecomefilled with liquid, the valve 58 can again be operated torecommunicate the compressed gas header with the inlet 52 to repeat thecycle.

Thus, the liquid can be removed from the tank substantially completelyto empty the tank without relying upon plumbing means to effectdisplacement. The system described provides for complete control withrespect to the flow of materials and it embodies, a complete cyclewherein the vapors removed can be reintroduced in a compressed state toeffect the desired displacement without introduction of foreignmaterials.

It will be apparent that the described system for the removal of liquidwill be relatively slow by comparison with the conventional means suchthat the removal system will be employed chiefly in the event of failureof the conventional means or in the event that such conventional meanspresent certain dangerous situations.

It will be understood that changes may be made in the details ofconstruction, arrangement and operation without departing from thespirit of the invention, especially as defined in the following claims.

I'claim: I

1. In the storage and transportation of a liquefied gas in tanks havingan inlet through which the liquid is introduced and an outlet throughwhich the liquid is discharged from the tank including a tubingextending downwardly to the bottom portion of the tanks and a poweroperated means for displacement of the liquid through the tubing to theoutlet, a liquid header for receiving the discharged liquid and meanscommunicating the outlet with the header, a sealed compartment withinthe tank and in the bottom thereof, a source of supply of pressurizedgas, a vapor header, a first opening in the compartment and meanscommunicating said first opening with said source of pressurized gas andthe vapor header, a second opening in the compartment and meanscommunicating the second opening with a pressure responsive valve whichcloses in response to pressure in the compartment and opens in responseto the loss of pressure within the compartment, a tubing having one endextending to the bottom portion of the compartment and communicatingwith the liquid header, a valve means in the first communicating meansshiftable in one position to communicate the first opening with saidsource of pressurized gas whereby the pressure responsive valve closesand liquid is forced from the compressed gas.

References Cited in the file of this patent UNITED STATES PATENTS1,460,389 Mauclere July 3, 1923 1,533,309 Durborow Apr. 14, 19251,823,406 Peaden Sept. 15, 1931 1,897,164 Endacott Feb. 14, 1933

